The Fluorescence-activated Cell Sorter is increasingly becoming a very powerful tool for cell bioligists and immunologists. The instrument is capable of separating and characterizing subpopulations of cells, organelles, chromosomes, and other particles of biological interest. In our laboratory the instrument will vastly facilitate our studies in cell cycle analysis, histocompatibility cell surface antigens, immunological mechanism of carcinogenesis, biochemistry and membrane metabolism, and inheritance of chromosomal aberrations. As far as we know, there is not a cell sorter within the state of Maine. The closest location of such an equipment is probably in Boston which is approximately 300 miles from Bar Harbor. The availability of a Cell Sorter at the Jackson Laboratory will not only benefit research staff at our institution but several universitities and research laboratories in the State of Maine; these include the University of Maine at Orono, the College of the Atlantic, the Mount Desert Biological Laboratory and the Bigelow Laboratory for Ocean Sciences.